As a professional groomer I see dogs in all stages of neglect. These two photos are from a three-year old Kerry male dog who was not groomed for one year.
The dog was in pain and did not want anyone to touch his coat. You can see the muzzle I needed to use. Off the grooming table this Kerry had a nice temperament.
The coat was so matted that when clipping, it was coming off in one piece. There was no other solution than to clipper the Kerry down to the skin.
We were able to save most of the fall and some of the beard.
After a long lecture the customer has promised to brush the dog every day, even when he has no hair. This will make it easy for both dog and owner to get used to the process.